In a copending application 08/261,978 filed Jun. 17, 1994 and assigned to the same assignee as the present invention a decorticating machine and method are described for decorticating lengths of kenaf which may be up to 12 feet. It has been discovered that harvesting kenaf by conventional forage chopping harvesters such as used for harvesting stripped corn stalks is especially convenient. Conventional harvesting methods, however, result in bulk kenaf in chopped lengths of two to five inches. This comprises both bast and core. Separating the bast from the core where the pieces of kenaf are typically about three to five inches in length presents special problems which cannot be handled by the machinery designed to handle stalks up to 12 feet in length. Hence the broad object of the present invention is to provide a method of separating bast from core wherein the kenaf has been forage harvested into chopped lengths of typically about three to five inches.